JP3572470B2 - Bellows mounting structure - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a bellows mounting structure used to hermetically seal an opening provided in a cylindrical housing for projecting a shaft while allowing the shaft to move.
[0002]
[Prior art]
For example, a rack housing extending in the left-right direction of the vehicle body is provided with a rack shaft slidably supported in the axial direction, and protruding ends of the rack shaft on both sides of the rack housing are connected to left and right steering wheels. The rack and pinion type steering device configured to perform steering by sliding the rack shaft in the axial direction, such as a rack and pinion type steering device, performs a predetermined motion including the axial length movement inside the cylindrical housing. There are many devices which are provided with a shaft body, a part of the shaft body is protruded outside from an opening at one or both ends of the housing, and a predetermined work is performed by using the movement of the protruding end. Used in industrial fields.
[0003]
In this type of device, an opening provided at the end of the housing for projecting the shaft is hermetically sealed while allowing the above-described movement of the shaft, so that foreign substances such as water, dust, etc. Sealing means for preventing intrusion into the inside is required, and bellows have been conventionally used as this kind of sealing means.
[0004]
As is well known, a bellows has a peripheral wall that forms a waveform in a cross section including a shaft, and a bellows-shaped main body tube that can expand and contract in the axial direction by deformation of these waveforms, and on both sides of the main body tube. A cylindrical body made of an elastic material having an annular portion (fixed ring) for fixing to a continuously provided object, and when used as the above-described sealing means, an outer surface of an opening edge of the housing; The fixing rings on both sides are externally fitted to and fixed to a part of the shaft body protruding from the opening, respectively, and are mounted so as to be bridged between the housing and the shaft body. With this attachment, the opening is covered with the main body cylinder to achieve sealing, and the movement (mainly movement in the axial length direction) of the shaft body can be allowed by the expansion and contraction of the main body cylinder.
[0005]
When the bellows is attached as described above, it is necessary to ensure that the fixed ring is fitted to the fitting ring and to ensure a high sealing property at the fitting portion. In particular, in the rack-and-pinion type steering device described above, when used as a sealing means between the rack housing and the rack shaft, the mounting position of the bellows may cause muddy water, sand dust, and the like to be flipped up by the wheels while the vehicle is running. It is important to improve the sealing performance at the fitting portion of the fixed ring because it is constantly exposed to foreign matter and may be immersed in water.
[0006]
On the other hand, in the use as a sealing means between the rack housing and the rack shaft, damage caused by the action of an external force during running of the vehicle, such as collision of flying stones flipped by wheels, is prevented, and heat generated in the engine room is prevented. In order to meet these demands, in recent years, resin-made bellows such as polyolefin-based elastomers have been widely used. . However, since the resin bellows is inferior in elasticity to general rubber bellows, it is more important to secure the sealing property at the fitting portion of the fixed ring.
[0007]
Conventionally, the inner diameter of the fixed ring is set by securing a sufficient interference with the outer diameter of the attachment target portion, and the fixed ring is fitted to the target portion in an extended state, while the fitting portion is A mounting structure that tightens the outer side with a tightening band and strongly presses the inner surface of the fixed ring against the outer surface of the target part to improve the adhesion between both sides, thereby improving the sealing performance and preventing the displacement of the fitting position. Is generally adopted.
[0008]
However, when such a mounting structure is adopted, especially in a resin bellows in which a sufficient interference is hardly secured due to lack of elasticity, the sealing performance at the fitting portion of the fixed ring is not sufficient, and Supply and exhaust of the inside and outside air due to expansion and contraction occur via the fitting portion, and there is a problem that foreign substances that enter the housing together with the supply and exhaust cannot be sufficiently prevented.
[0009]
Japanese Patent Application Laid-Open No. Hei 6-313480 proposes to improve the sealing performance at the fitting portion of the fixed ring of the bellows. Figure 3 is an enlarged view of the stationary ring near the bellows disclosed in Japanese Patent Laid-Open No. 6-313480, Fig. 4 is an explanatory view of the installation procedure. As shown in FIG. 3 , the bellows 3 includes a bellows-shaped main body tube 3a in which only one mountain shape of the peripheral wall is shown, and a fixed ring 3b connected to one side of the main body tube 3a. An annular protrusion 3c is provided on the inner surface of the ring 3b, and an annular concave groove 3d is provided on the outer surface of the ring 3b so as to align with the annular protrusion 3c.
[0010]
When the fixed ring 3b is fitted to the opening edge of the housing H to be attached, the bellows 3 provided with such a fixed ring 3b, as shown in FIG. 4 (a), has an annular projection 3c on the inner surface of the fixed ring 3b. Is pushed up by the fitting surface of the housing H, and the corresponding portion on the outer surface rises with the concave groove 3d formed in the portion expanded. And Thus, in a fixed state obtained by tightening the band 4 fastening the outer stationary ring 3b in this state, as shown in FIG. 4 (b), on both sides of the groove 3d is locally pressed, the inner surface The annular protrusion 3c formed at the corresponding portion of the opening is crushed between the outer surface of the opening edge and the outer periphery of the opening edge, and a tight crimping state occurs therebetween, so that a good sealing property is secured over the entire circumference. It is supposed to get.
[0011]
[Problems to be solved by the invention]
However, in the mounting structure as described above, the fastening band 4 to be mounted as shown in FIG. 4 (b) is partially unstable because the raised portions on both sides of the concave groove 3d partially support the flat inner surface. In this case, there is a problem in that the supporting force in the axial direction is insufficient, and the other purpose of preventing displacement in the axial direction cannot be achieved.
[0012]
The concave groove 3d on the outer surface of the fixed ring 3b is provided to absorb the outward bulge caused by the crushing of the annular projection 3c on the inner surface to avoid the above-described inconvenience. If the cross-sectional size of the projection 3c is excessively large, the annular projection 3c is insufficiently crushed to obtain a desired sealing performance, and if it is too small, absorption of the bulge is not sufficient. As a result, the mounting state of the tightening band 4 becomes unstable, and the displacement in the axial length direction is likely to occur.
[0013]
That is, in the bellows mounting structure disclosed in JP-A-6-313480, it is necessary to ensure high shape accuracy in the annular projection 3c and the concave groove 3d in order to achieve a desired purpose. It is difficult to obtain satisfactory shape accuracy by blow molding generally disclosed in the production of this type of bellows, and the above-mentioned inconvenience cannot be solved.
[0014]
The present invention has been made in view of such circumstances, and a bellows used to seal an opening provided for projecting a shaft in a cylindrical housing, while ensuring high sealing performance, It is an object of the present invention to provide a mounting structure that can be mounted without displacement in the axial direction due to the movement of the shaft.
[0015]
[Means for Solving the Problems]
The bellows mounting structure according to the present invention uses a bellows in which fixed rings are continuously provided on both sides of a bellows-shaped main body tube that can expand and contract in the axial direction, and the edge of the end opening of the cylindrical housing. The fixed rings are externally fitted to the outer surface and a part of the shaft protruding from the opening, respectively, and tightened from the outside by a tightening band to allow the movement of the shaft with respect to the housing by expansion and contraction of the main body cylinder. while, in the mounting structure of the bellows for sealing the opening tightly, the fixed one or more sealing projection on the inner surface is circumferentially provided with an annular ring, the outer surface of the fixed ring during the tightening the And a pressing projection protruding from an inner surface of the tightening band so as to press the sealing projection while avoiding a corresponding portion of the sealing projection.
[0016]
In the present invention, when the fixed ring of the bellows is externally fitted to the opening edge of the housing to be fitted, the sealing projection provided on the inner surface of the fixed ring locally contacts the outer surface of the opening edge. When the tightening band is tightened to the outside of the fixed ring, the sealing protrusion is crushed between the sealing ring and the outer surface of the opening edge portion, and a sealed state over the entire circumference is secured. Pressing projections projecting from the inner surface of the band press the fixing ring from the outside, and both sides of the sealing projection are pressed against the outer surface of the opening edge to prevent displacement in the axial direction .
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments. FIG. 1 is an enlarged sectional view of a main part of a bellows and a tightening band used for carrying out the present invention. The bellows 1 used in the embodiment of the present invention includes a bellows-shaped main body tube 1a in which only one chevron shape of a peripheral wall is shown, and a fixed ring 1b connected to one side of the main body tube 1a. On the inner surface of the fixed ring 1b, three sealing projections 1c, 1c, 1c each having a semicircular cross-sectional shape are formed in a ring shape at substantially equal intervals in the axial direction.
[0018]
The bellows 1 is made of an elastic material such as resin or rubber, and the diameter of the fixed ring 1b can be increased within an appropriate range by applying an external force. Is used to fix one side of the bellows 1 to the object.
[0019]
The tightening band 2 used in the embodiment of the present invention together with the bellows 1 as described above is a metal ring formed by molding a thin plate made of a material having high elasticity such as spring steel into a ring having a length corresponding to the fixed ring 1b. In the same manner as that conventionally used for the same purpose, by a proper operation from the outer diameter side, a tightened state having an inner diameter sufficiently smaller than the outer diameter of the fixed ring 1b, and It is designed to be able to be restrained in a fitted state having an inner diameter larger than the diameter.
[0020]
As shown in the drawing, a pressing projection 2a is provided on the inner surface of the tightening band 2 so as to project inward. The illustrated pressing projection 2a is formed by indenting the peripheral wall of the fastening band 2 inward, and two annular projections provided on the inner surface of the fixed ring 1b at intervals substantially equal to the sealing projections 1c, 1c, 1c. It is configured as
[0021]
FIG. 2 is an explanatory diagram of a procedure for mounting the bellows 1 using the tightening band 2 as described above. In the figure, reference numeral H denotes a housing to be attached. The bellows 1 is attached to one side of the housing H and fixed to the outer periphery of an opening edge provided for projecting a shaft (not shown), as in the conventional case. The ring 1b is fitted, and the outside of the fixed ring 1b is tightened by the tightening band 2.
[0022]
FIG. 2A shows a state in which the fixed ring 1b is fitted around the outer periphery of the opening edge of the housing H. The sealing projections 1c, 1c, 1c are provided around the inner surface of the stationary ring 1b, and when the stationary ring 1b shown in FIG. 2A is fitted, the sealing projections 1c, 1c, 1c are provided. Are in local contact with the outer peripheral surface of the opening edge.
[0023]
The tightening band 2 is restrained in the above-mentioned fitted state, and is loosely fitted to the outside of the housing H before the fixed ring 1b is fitted. As shown by a broken line in FIG. After the outer periphery of the stationary ring 1b has been fitted, the stationary ring 1b is moved in the axial direction, and is positioned outside the stationary ring 1b as shown by a solid line in FIG. You.
[0024]
This positioning is such that the pressing projections 2a, 2a provided on the inner surface of the tightening band 2 are positioned between the central sealing projection 1c and the sealing projections 1c, 1c on both sides of the inner surface of the fixed ring 1b. However, high accuracy is not required, and, for example, rough positioning such that the periphery of the tightening band 2 is aligned with a matching mark appropriately formed on the outer surface of the fixed ring 1b is sufficient. In the figure, a recess indicating the fastening position of the fastening band 2 is formed on the outer surface of the stationary ring 1b, and the edge of the recess is used as a matching mark.
[0025]
The fixing of the bellows 1 is realized as shown in FIG. 2B by releasing the restraint of the tightening band 2 after the above positioning is completed. When the restraint is released, the tightening band 2 attempts to be in a tightened state in which the inner diameter is reduced, and a tightening force is applied to the fixed ring 1b aligned inward. At this time, the sealing projections 1c, 1c, 1c projecting in an annular shape on the inner surface of the fixed ring 1b are crushed between the outer surfaces of the opening edges of the housing H, and the entire circumference is interposed between them. As a result, the pressing protrusions 2a, 2a on the inner surface of the fastening band 2 locally press the outside of the fixed ring 1b, so that the inner surface of the fixed ring 1b The portion of the fixing ring 1b that is aligned with the pressing projections 2a, 2a, that is, the portion between the sealing projections 1c, 1c, 1c, is strongly pressed against the outer surface of the opening edge of the housing H, and the axial length of the fixed ring 1b with respect to the housing H. It is possible to prevent displacement in the direction.
[0026]
According to the bellows mounting structure as described above, the sealing projections 1c, 1c, 1c projecting from the inner surface of the fixed ring 1b and the pressing projections 2a, 2a projecting from the inner surface of the tightening band 2 act. The bellows 1 can be attached to the opening end of the housing H while ensuring good sealing performance at the fitting portion of the fixed ring 1b and effectively preventing displacement in the axial direction after the attachment. Become.
[0027]
The sealing property is obtained by crushing the sealing projection 1c on the inner surface of the fixed ring 1b by tightening the fastening band 2, and the sealing projection 1c is provided around the entire circumference of the fixed ring 1b. It is necessary that the projection is a circular projection. The number of the sealing projections 1c is not limited to three as shown, but may be one or two, or may be four or more. The cross-sectional shape of the sealing projection 1c is not limited to the semicircular shape shown in the drawing, and other cross-sectional shapes can be adopted as long as they are substantially uniform over the entire circumference. Further, the peripheral position of the sealing projection 1c only needs to be roughly accurate to the extent that the above-described matching relationship can be obtained between the pressing projections 2a and 2a on the tightening band 2 side.
[0029]
The pressing projection 2a protruding from the inner surface of the tightening band 2 is shown in FIGS. 1 and 2 as an annular protrusion having a trapezoidal cross section formed by indenting the peripheral wall of the tightening band 2 inward. However, the mode of forming the pressing projection 2a is not limited to this, and unlike the sealing projection 1c on the inner surface of the fixed ring 1b , the pressing projection 2a does not need to be an annular projection over the entire circumference.
[0030]
The pressing projections 2a shown in FIGS . 1 and 2 can be formed simultaneously in the step of forming the plate material into an annular body to obtain the tightening band 2, and have a predetermined shape accuracy and positional accuracy without subsequent processing and finishing. Is obtained. Further, the number of the pressing projections 2a is not limited to the two shown in the drawing, and is appropriately determined according to the number of the sealing projections 1c.
[0031]
【The invention's effect】
As described above, in the bellows mounting structure according to the present invention, when the fixed ring of the bellows is externally fitted to the opening edge portion of the housing to be fitted, the sealing projection provided on the inner surface of the fixed ring has the housing. Locally abuts the outer surface of the opening edge of the opening , and the subsequent tightening of the tightening band produces a close contact portion over the entire circumference at a substantial position of the sealing protrusion, ensuring the sealing performance, and at the same time, the inner surface of the tightening band. The projecting pressing projections tighten the fixing ring at the portion where the sealing projections are not formed, and increase the contact area with the outer surface of the housing to prevent displacement in the axial direction. The present invention has an excellent effect, for example, in that the bellows can be attached to the opening provided at the end of the shaft without a positional displacement in the axial direction while ensuring high sealing performance.
[Brief description of the drawings]
FIG. 1 is an enlarged sectional view of a main part of a bellows and a tightening band used for carrying out the present invention.
FIG. 2 is an explanatory view showing an embodiment of a bellows mounting structure according to the present invention.
FIG. 3 is an enlarged view around a fixed ring of a conventional bellows with improved sealing performance.
FIG. 4 is an explanatory diagram of a procedure for attaching the bellows shown in FIG . 3;
[Explanation of symbols]
1 bellows
1b Stationary ring
1c Sealing protrusion 2 Tightening band

Claims (1)

A bellows is used in which fixed rings are connected to both sides of a bellows-shaped main body cylinder that can expand and contract in the axial direction, and an outer peripheral edge of an end opening of a cylindrical housing and a shaft protruding from the opening are used. Each of the fixed rings is externally fitted to a part of the body, and is tightened from the outside by a tightening band to allow the movement of the shaft body with respect to the housing by expansion and contraction of the main body cylinder, and hermetically seal the opening. in the mounting structure of the bellows, avoiding and one or more sealing projections are circumferentially provided at an annular inner surface of the stationary ring, the corresponding portion of the fastening the sealing projection of the outer surface of the stationary ring in pressing And a pressing projection protruding from an inner surface of the tightening band.

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